We say, God knows better, but never God understands better. When I say, for instance, I understand, I mean to be deep, but when I say, I understand, I mean to be satisfactory, and assuring. In the domain of physical knowledge, therefore to know is the ultimate. We know things through understanding them; to know is universal, but to understand is personal and confined to the context of the mind in a situation.
In the process of acquisition of knowledge, understanding needs to take place at every step of the way. Every bit of knowledge we acquired we need to consolidate it with what was acquired before. This is much like pieces of a jigsaw puzzle fitting into their places, or bricks being set in their positions.
The confusion is for an obvious reason that we cannot know anything merely by being informed about it, but with understanding taking place. If to know is the ultimate objective, then to understand is the how that objective was achieved, i.e. if to eat food were the aim then taking a bitesize, chewing in the mouth and swallowing is like understanding.